为什么我的 python kivy 登录表单不起作用？

Question

我使用 PostgreSQL 创建了一个 Kivy 登录表单。

    def login(self):
        # get email and password from TextInputs
        email = self.root.ids['login_screen'].ids['email']
        password = self.root.ids['login_screen'].ids['password'].text

        con = psycopg2.connect(
            host="localhost",
            database="abc",
            user="postgres",
            password="123")
        cur = con.cursor()
        #get password from db 
        sql = "SELECT password FROM regdata WHERE email=%s"
        val = [email.text]
        cur.execute(sql, val)
        rows = cur.fetchall()
        for row in rows:
            #tpassword is variable which helps to check password(if password = password we can sign in)
            tpassword = row[0]
            print(password)
            print(tpassword)
            if password == tpassword:
                self.change_screen('home_screen')

        con.commit()
        cur.close()
        con.close()

所以，当我打印变量密码和密码时，它们的值是相等的，但我不能改变屏幕。

感谢帮助！

Answer 1

这样做ScreenManager和Screen效率更高。

主文件

from kivy.app import App 
from kivy.lang import Builder
from kivy.core.window import Window
import pyttsx3
from kivy.uix.screenmanager import ScreenManager, Screen, NoTransition
from kivy.properties import ObjectProperty, NumericProperty

Window.size = (800, 600) #setting screen size to 800x600

asset = Builder.load_file('styles.kv') #loading styles of widgets from 'styles.kv'

class ScreenOne(Screen): #making a screen
    pass

class Main(Screen): #making another screen
    pass

class Manager(ScreenManager): #making a manager to handler screens
    screen_one = ObjectProperty(None)

class MainApp(App): #making the main app
    def build(self):
        m = Manager(transition=NoTransition()) #setting the manager to manage screens for this app
        return m

    def login(self): #check function to check email and password
        email = self.root.ids.screen_one.ids['email']
        password = self.root.ids.screen_one.ids['password'].text

        con = psycopg2.connect(
            host="localhost",
            database="abc",
            user="postgres",
            password="123")
        cur = con.cursor()
        #get password from db 
        sql = "SELECT password FROM regdata WHERE email=%s"
        val = [email.text]
        cur.execute(sql, val)
        rows = cur.fetchall()
        for row in rows:
            #tpassword is variable which helps to check password(if password = password we can sign in)
            tpassword = row[0]
            print(password)
            print(tpassword)
            if password == tpassword:
                self.root.current = 'screen1'

        con.commit()
        cur.close()
        con.close()

MainApp().run() #running the app

styles.kv

<Main>:
    FloatLayout:
        anchor_x: 'center'
        anchor_y: 'top'

        TextInput:
            id: email
            size_hint: (None, None)
            height: 60
            width: 250
            pos: 270, 400
            hint_text: 'Type your e-mail here'

        TextInput:
            id: password
            password: True
            size_hint: (None, None)
            height: 60
            width: 250
            pos: 270, 320
            hint_text: 'Type your password here'

        Button:
            id: submit
            size_hint: (None, None)
            size: 125, 50
            text: 'Submit'
            pos: 335, 250
            on_press: app.login()

<ScreenOne>:
    FloatLayout:
        anchor_x: 'center'
        anchor_y: 'top'

        TextInput:
            id: input
            size_hint: (None, None)
            hint_text: 'This is your home screen'
            height: 300
            width: 400
            pos: 200, 200

<Manager>:
    id: screen_manager
    screen_one: screen_one

    Main:
        id: screen_one
        name: "main"
        manager: screen_manager

    ScreenOne:
        id: screen_two
        name: "screen1"
        manager: screen_manager